GB2232298A

GB2232298A - Control devices for microwave ovens

Info

Publication number: GB2232298A
Application number: GB9012042A
Authority: GB
Inventors: Gi In Lee
Original assignee: Gold Star Co Ltd
Current assignee: LG Electronics Inc
Priority date: 1989-05-31
Filing date: 1990-05-30
Publication date: 1990-12-05
Anticipated expiration: 2010-05-30
Also published as: JPH033607U; GB9012042D0; JP2514010Y2; US5134262A; DE4017422C2; DE4017422A1; GB2232298B

Description

CONTROL DEVICE FOR A MICROWAVE OVEN The present invention relates to a

control device for a microwave oven, and to a microwave oven incorporating the device. In an existing microwave oven, a power selection switch for a cooking operation, as shown In Fig. 1(a), and a defrosting device, as shown in Fig. 1(b), are separately provided. The power selection switch for cooking comprises a 10 sensitive switch 31, a cam 32 for on/off operation of the contact 311 of the switch 31, a plate spring 33 resiliently supporting the cam 32, a main body 35,35' supporting the spring 33, and a shaft 34, the external end of which serves as a mounting for a knob 37 which 15 turns in the directions of arrows 36 and 36'. The defrosting device shown in Fig. 1(b) comprises a synchronous motor 38, a gear 40 mounted on the shaft 39 of the motor 38, a gear 41 engaging with the gear 40, a cam 42 mounted on a rotary shaft 43, and a 20 sensitive switch (e.g. microswitch) 44 mounted on a side of the cam 42. To select the defrosting operation using the above construction, the knob 37 is turned in the direction of the arrow 36'. The cam 32 which is mounted in axial 25 alignment with the knob 37 on a shaft 34 turns in the same direction 36' and turns off the contact 31' of the switch 31, as shown in Fig. 1(a). Concurrently, the synchronous motor 38, with power on, rotates and turns the gear 40 mounted on the motor shaft 39 so as to 30 drive the gear 41 in engagement with the gear 40 and so rotate the cam 42 on the common shaft 43. This causes the sensitive switch 44 to switch on/off cyclically with a period determined by the arcuate extent of the cam 42. 35 Thus, for a defrosting operation, the switch 31 is turned off while the switch 44 switches on/off in 1 1 cycles.

To select the cooking operation, the knob 37 in the power selection switch in Fig. l(a) is turned in the direction of the arrow 36 opposite to the direction for the defrosting function and causes the cam 32 to rotate in the same direction thereby turning on the contact 311 of the switch 31.

When the switch 31 is turned on, the cooking function is selected and operates irrespective of the on/off operation of the defrosting switch 44.

A disadvantage of having separate devices respectively for cooking and defrosting operations as in the above construction is that the technical construction is complicated resulting in a high manufacturing cost and the problem of difficulties in assembly.

According to the present invention, there is provided a control device for a microwave oven, comprising: a knob operable to be pushed and/or pulled to select between a first or second function of the oven, and operable to be rotated to set a parameter of the selected function; a first shaft fixed to said knob at one end thereof; a coupling receiving the other end of said first shaft and an end of a second shaft, and including reciprocating means for allowing the first shaft to reciprocate relative to the second shaft; the second shaft being engaged with an operating unit of the microwave oven; first and second actuators coaxially fixed on said first shaft for being simultaneously rotated therewith; and switching means connected to the operating unit and arranged to be contacted by either said first or second actuator, as determined by the reciprocating movement of the first shaft.

A development of the present invention also provides a microwave oven incorporating such a control A 1 device.

Thus, an embodiment of the invention can integrate the separate devices previously provided for cooking and defrosting respectively into a single control device enabling simple manipulation and operation of the microwave oven.

Reference is made, by way of example, to the accompanying drawings in which:

Fig. 1 (a) is a perspective view of an existing power selection switch; Fig. 1 (b) is a perspective view of an existing defrosting device; Fig. 1 (c) is a front view of an existing control panel; Fig. 2 is a perspective view of a control device embodying the present invention; Figs. 3 (a) and (b) show the positions of a control knob for cooking and defrosting respectively in the device of Fig. 2; Fig. 4 (a) is a sectional view of a coupling in the device of Fig. 2; Fig. 4 (b) is a sectional view along the line A-A in Fig. 1(a); and Fig. 5 is an exploded perspective view of a coupling guide and a guide plate for an outer casing.

An embodiment of the present invention will now be described in detail.

As shown in Fig. 2, a timer 1 has protruding from it a shaft 2 mounting a coupling (joint) 3 on its end, the coupling 3 having a knob shaft 4 protruding from it at one end. The shaft 4 axially supports a wheel 5 and a lobed wheel 6 relating to the cooking and defrosting functions respectively (these being inserted over a mid-section of the shaft) and also carries a knob 7 at its free end. 1.

The wheels 5 and 6 concerned respectively with t 1 cooking and defrosting are arranged such that the wheel periphery or lobe tips make contact with a sensitive switch 8 in order to select either of the cooking and -defrosting functions.

As shown in Figs. 4 and 5, the coupling 3 comprises an outer casing 9 containing a reciprocating member 11 mounted for reciprocating movement in the directions 10 and 101, a guide member 13 arranged for movement in the vertical directions 12 and 121 within the member 11, a guide plate 91 resiliently mounted on the top side of the outer casing 9 and defining the possible movement of the guide member 13, and a stopper C on the guide plate 9, protruding toward the guide member 13. There is also provided,a resilient spring 14 for imparting a spring return action to the movement of the reciprocating member 11 in the arrow direction 101 within the casing 9. Referring to Fig. 5, on the top of the guide member 13 there is formed in the centre of portion c a recess 13a for controlling the stopper C, having stepped face portions b for advancing, c for catching and f for releasing.

In use of the above control device, a first push to the knob 7 as shown in Fig. 3(a) results in the selection of defrosting function, and another push to the knob makes it pop out and select the cooking function. With the defrosting function selected, a turn of the knob 7 in the direction of an arrow 71 (Fig 2) sets the timer 1 via shaft 7, coupling 3 and timer shaft 2 to the time necessary to defrost the food in the oven. Meanwhile, the contact 8' of the switch 8 switches in and out of contact with the lobes of wheel 6 in cycles having a period determined by the lobe configuration on the periphery of the wheel 6. Variations in the shape and number of lobes of the wheel may suitably adjust the defrosting time of food, as desired.

b t To select the cooking function after a defrosting operation, the knob 7 is gently pushed once again and then released whereby the action of coupling 3 causes it to pop out in the direction 101 along with the shaft 4 and the wheels 5 and 6. In such a way the round peripheral face of the wheel 5 is held in steady contact with the contact 81 of the switch 8 thus enabling the cooking operation.

In switching from the cooking function to the defrosting function, the coupling 3, controlling the back and forth movements of the knob shaft, moves in the direction 10 and the reciprocating member 11 is positioned on line "A". As shown in Fig. 4(a) and Fig. 5, the guide member 13 moves in the direction 121 under the action of the stopper C of the guide plate 9 and follows the slope of the facing portion a to advance and set the stopper C at position-"C" of the guide member 13. Upon the removal of the pushing pressure the stopper 9" holds the guide member 13 at position "D" under the resilient force of the spring 14 and by the action of the inclined faces of stopper 9" and the portion c. The state of stoppage determines the position of the coupling 3 and hence the selection of the defrosting function, the knob 7 not popping out from the control panel 5.

Thereafter, in order to switch from the defrosting function to a cooking operation, the knob 7 is again pushed, advancing the guide member 13 such that the catch face c is unhooked from the stopper 9" so that the release face d comes under the stopper C from which it unhooks the member 13. Upon subsequently removing the pushing pressure, the knob 7 is returned to its original position by the resilient force of the spring 14 and the projecting hook of the reciprocating member 11' stopped by the stopper 9" of the outer casing 9.

1 1 1 1 1 Thus, the cooking and defrosting functions of a microwave oven may be alternately selected and executed by moving the knob shaft through the stroke distance "S" in Fig. 4, so as to make one or other of the wheels 5 5 and 6 connect with the sensitive switch 8.

Thus, an embodiment of the present invention allows an accurate time for defrosting food to be set by mounting a defrosting wheel on the same shaft as used to set a cooking time, and the defrosting time set for the oven may be adjusted by changing the peripheral shape of the wheel concerned with the defrosting function. Further, the integral construction for combined cooking and defrosting functions facilitates manufacture and manipulation of the microwave oven saving space for other purposes and with a consequent reduction in manufacturing cost and assembly problems.

It will be understood that although the above embodiment of the invention is provided for selecting between a cooking function and a defrosting function in a microwave oven having both functions, the invention may also be applicable to selection between other functions of a microwave oven, where a parameter (e.g. time) pertaining to at least one of the functions also needs to be set.

1 i

Claims

Claims 1. A control device for a microwave oven, comprising: a knob

operable to be pushed and/or pulled to select between a first or second function of the oven, and operable to be rotated to set a parameter of the selected function; a first shaft fixed to said knob at one end thereof; a coupling receiving the other end of said first shaft and an end of a second shaft, and Including reciprocating means for allowing the first shaft to reciprocate relative to the second shaft; the second shaft being engaged with an operating unit of the microwave oven; first and second actuators coaxially fixed on said first shaft for being simultaneously rotated therewith; and switching means connected to the operating unit and arranged to be contacted by either said first or second actuator, as determined by the reciprocating movement of the first shaft.
2. A control device as claimed in claim 1, wherein the first and second functions are-a cooking function and a defrosting function, wherein the parameter is a cooking or defrosting time, and wherein the operating unit comprises a timer for operating during a time period set by rotation of the knob.
3. A control device as claimed in claim 2, wherein the first actuator is a round wheel for steadily contacting the switching means, and the second actuator is a lobed wheel for intermittently contacting the switching means, during the time period set by rotation of the knob.
4. A control device as claimed in claim 3, wherein the round wheel and the lobed wheel are separated by a distance equal to a range of reciprocating movement of 1 7 the first shaft, whereby said switching means contacts selectively the round wheel or the lobed wheel as the first shaft reciprocates back and forth.
5. A control device as claimed in claim 3 or 4, wherein a plurality of lobes are provided around the edge of the lobed wheel for contacting the switching means periodically.
6. A control device for a microwave oven, substantially as h6reinbefore described with reference 10 to Figures 2 to 5 of the accompanying drawings.
7. A microwave oven incorporating a control device as claimed in any one of the preceding claims.

Q Published 1990 atThe Patent Office. State House. 66'71 High Holborn. LondonWCIR4TP.Further copies maybe obtainedfrom The Patent Office. Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent, Con. 1/87